> Simple check access path with "EXPLAIN SELECT ... ". Now you can see if > index or key is used. For further information please read manual section > 'Background Knowledge/SQL Optimizer'.
Also, statistics should be up to date for that table. robert > Gert > > -----Urspr�ngliche Nachricht----- > Von: Christoph Weser [mailto:[EMAIL PROTECTED] > Gesendet: Freitag, 18. M�rz 2005 08:50 > An: Grossmann, Gert > Betreff: AW: Index use vs Table Scan! > > > Hello Gert! > > Thanx for your quick replay and a simple answer.....how do I check the > access paths and how to interpret results? > There are right now some real data in the table...a few million rows. > > Thanx a lot for your help! > > Chris > > -----Urspr�ngliche Nachricht----- > Von: Grossmann, Gert [mailto:[EMAIL PROTECTED] > Gesendet: Freitag, 18. M�rz 2005 07:02 > An: maxdb (E-Mail) > Betreff: AW: Index use vs Table Scan! > > > MaxDB has a cost based optimizer. Without any data in relations there is > no > difference between table scan vs. index access. > Fill your releation "s_event" with real data and then check access pathes. > > Gert > > -----Urspr�ngliche Nachricht----- > Von: Christoph Weser [mailto:[EMAIL PROTECTED] > Gesendet: Donnerstag, 17. M�rz 2005 17:29 > An: maxdb (E-Mail) > Betreff: Index use vs Table Scan! > > > Hello All! > > I'm running 7.4.3.32 on a W2K system. > > I have the table: > > create table s_event ( > EID FIXED(38,0) NOT NULL, > ETID FIXED(38,0) NOT NULL, > SID FIXED(38,0) NOT NULL, > CID FIXED(38,0), > eventtime FIXED(38,0) NOT NULL, > data LONG BYTE, > > FOREIGN KEY(ETID) references s_eventtype(ETID) > ) > > // > create index s_event_x1 on s_event(EID) > // > create index s_event_x2 on s_event(ETID) > // > create index s_event_x3 on s_event(SID) > // > create index s_event_x4 on s_event(CID) > // > create index s_event_x5 on s_event(eventtime) > > When I do an > > explain select * from s_event where (eventtime < 1111056567313) > > the result is a table scan! > > On the other hand, when I do an > > explain select * from s_event where (eventtime = 1111056567313) > > The DB does an index scan and it uses the index s_event_x5. > > > Is there a way for the first statement, that the db also does an index > scan > and not the expensive table scan??? > Why isn't an index also used in the first statement? Any explanations? > > Thanx a lot to everyone!!! > > Chris > > -- > MaxDB Discussion Mailing List > For list archives: http://lists.mysql.com/maxdb > To unsubscribe: > http://lists.mysql.com/[EMAIL PROTECTED] > > > -- > MaxDB Discussion Mailing List > For list archives: http://lists.mysql.com/maxdb > To unsubscribe: > http://lists.mysql.com/[EMAIL PROTECTED] > > -- > MaxDB Discussion Mailing List > For list archives: http://lists.mysql.com/maxdb > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] > -- DSL Komplett von GMX +++ Superg�nstig und stressfrei einsteigen! AKTION "Kein Einrichtungspreis" nutzen: http://www.gmx.net/de/go/dsl -- MaxDB Discussion Mailing List For list archives: http://lists.mysql.com/maxdb To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
